The subject matter of this invention relates to water or water co-blown polyurethane foam (e.g., an air or sound barrier in interior walls and ceilings in construction applications), and foam precursors used in space-filling applications such packging foams, spray-applied sound and air barriers in interior walls, insulating spray-applied roofing foam, pour-in-place foam, and other construction applications. The present invention also provides a method for making a water or water co-blown, polyurethane (PUR) foam, especially low density spray-applied PUR foams.
In conventional polyurethane foam manufacturing methods, the isocyanate portion of a low density water-blown polyurethane formulation is referred to as the A-side, while the isocyanate-reactive portion is referred to as the B-side. In a spray-applied PUR formuation, the A-side and the B-side are stored separately, and typically combined at the point of application through a high pressure spray application equipment. The B-side typically contains water, polyol, flame retardants, antioxidants, silicone surfactants, cell openers, and other additives, all pre-mixed together. Formulations for this type of material application contain amounts of water ranging from about 2 to about 30 weight percent in the B-side. The water acts as both a chemical blowing agent by reacting with isocyanate to produce CO2 gas, and a physical blowing agent by releasing as steam from the heat of the polyurethane and polyurea forming chemical reactions. This relatively high percentage of water in the formulation can lead to phase instability, in which the water is no longer completely soluble in the other components of the B-side. Phase separation can become a problem for formulators who prepare, store, and ship the B-side premix to in 55 gallon drums. Spray applicators in the field have no way to see inside the steel drum to visualize the phase separation, and mixing of the material in the field can be very difficult and it is always not known if complete mixing has been achieved. Phase separation of the components can lead to differences in reactivity, cell structure, physical properties as well as the consistency of the sprayed PUR foam.
To address these problems, emulsifiers can be added to the formulation. An emulsion is generally defined as a stable mixture of two or more immiscible or unblendable liquids. The prior art describes emulsifiers that are in the class of chemical compounds known as nonylphenolethoxylates, or NPE's (a general structure of an NPE is shown in FIG. 1). GB 1139510, GB 1001946, and GB 886636 and WO 00/46266 are illustrative of NPE emulsifiers and describe the general methods of preparing polyurethanes, which may include the incorporation of various additives including surface-active agents such as oxyethylated fatty alkyl phenols (NPE's), oxyethylated fatty alcohols (alkylethoxylated alcohols), foam stabilizing agents such as silicone polyethers, among other conventional additives and agents. The prior art does not teach how to use the surface active agents, ranges of HLB's for the surface active agents, that certain structures are more efficient in high water systems, or formulations that are free or substantially free of NPEs.
The disclosure of the previously identified patents and patent applications is hereby incorporated by reference.
In recent years, concerns have been raised that some NPE's may exhibit weak estrogen-like properties, although much weaker than naturally occurring estrogen estradiol, or may be endocrine disruptors. While there are currently no use restrictions in the United States, NP and NPE's are being evaluated by the Environmental Protection Agency under the new Chemical Action Plan (CAP) program. Therefore, there is a need in this art for spray foam formulations which are NPE-free.